Extruded catalysts with magnetic properties for biodiesel production

Abstract

The aim of this work was to evaluate the performance of different extruded catalysts containing K2CO3 as active phase and adding conveniently γ-Al2O3 and/or sepiolite and magnetic particles on the biodiesel production from sunflower oil by the ethanolic route. Firstly, the content of the Fe3O4 on the catalyst (0.1, 0.2, 0.3, and 0.4 g Fe3O4/g of K2CO3/γ-Al2O3), after calcination step, was evaluated to verify the separation facility of the catalysts with magnetic properties from reactional medium, using an external magnetic field, at the end of biodiesel synthesis. After that, three different catalysts were considered for comparative purposes: (a) K2CO3/γ-Al2O3; (b) K2CO3/γ-Al2O3/Fe3O4; (c) K2CO3/γ-Al2O3/Sepiolite/Fe3O4 and subsequently characterized by dynamometry, TGA, SEM, VSM, BET, and XRD to determine their mechanical, structural, magnetic, and textural properties. However, their catalytic activities were determined through biodiesel production that was carried out in a glass volumetric reactor during 4 h, under magnetic stirring with 5% wt. of the catalyst and oil: ethanol molar ratio (1: 12) at 80°C reaction temperature. The best result, i.e., around 88% of biodiesel conversion, was obtained with catalyst K2CO3/γ-Al2O3/Sepiolite/Fe3O4 which showed also satisfactory textural and mechanical strength properties comparatively with the other catalytic derivatives. In addition, no agglomeration of the particles was observed during the reaction, and the magnetic property of this catalytic system was satisfactory for adequate separation from reactional medium seeking further reuse. The attained results are attractive for possible implementation at industrial scale and can be considered to mitigate drawbacks which resulting by using of homogeneous catalysts in the conventional processes.